1. Field of the Invention
This invention generally relates to running cylinders of a rotary printing press and, specifically, to an apparatus for adjusting expansion bands on the running cylinder to change its effective diameter while the running cylinder is rotating.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97-1.99
Rotary printing presses employ numerous running cylinders. It is well known to provide these running cylinders with adjustable expansion bands in order to slightly increase or decrease the effective diameter of the cylinder. A folder of a rotary press folds the assembled webs of paper, cuts the webs into a product and then folds the product. The correct draw through the folder for a full range of thickness of product and minimization of "dog ears" and paper tears are achieved in the running cylinder of the folder, or folding cylinder, through provision of several sets expansion bands.
In some known presses, it is necessary to stop the press and adjust the expansion bands only after the running cylinder has stopped rotating which disadvantageously interrupts the production of printed product. The folding cylinder is provided with a band box for adjusting the expansion bands mounted to an end of the folding cylinder at a working area location within a peripheral annular band encompassing the outer third of the radius of the folding cylinder. The band box, being carried by the folding cylinder in the working area, revolves around the axis of rotation of the running cylinder and is therefore not accessible for making the manual adjustments while the running cylinder is rotating during operation of the press. In addition, the presence of large mechanisms in the working area, including a plurality of band adjustment studs and pin lever shafts and their associated cam followers and actuators and other obstacles, makes it impossible to access the band box from the end of the cylinder during rotation. Accordingly, in these known units, an operator uses a wrench to manually turn an adjustment shaft on the band box to move the expansion bands only after the folding cylinder is brought to a complete stop.
A complicated dynamic mechanism, shown in U.S. Pat. No. 4,936,516 of Mukai issued Jun. 26, 1990 is disadvantageously located in the working area. This mechanism utilizes two sun gears mounted on a plain bearing of the folding cylinder journal and a pin cam and its bearings mounted to a hub of the sun gear. However, the additive accumulation, or stack up, of tolerances and operational forces of this mechanism is deleterious to long life of the operating components and can make adjustment of the sun gear difficult. In addition, in this known Japanese mechanism, it appears that maintenance or replacement of parts disadvantageously requires major disassembly of the cylinder and its complex arrangement of numerous components and reboring of the journal of the running cylinder. Moreover, it appears that the known Japanese mechanism is not suitable for retrofitting to an existing folding cylinder.
Another problem with the dynamic expansion band adjustment mechanism is that once the adjustment is made, affirmative action must be taken to lock the adjustment in place. If such affirmative locking action is inadvertently not taken by the operator, then the selected adjustment will be altered during operation of the press by forces executed by the work product on the expansion bands.